1 /* Copyright (C) 2006-2016 B.A.T.M.A.N. contributors: 2 * 3 * Simon Wunderlich, Marek Lindner 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of version 2 of the GNU General Public 7 * License as published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, see <http://www.gnu.org/licenses/>. 16 */ 17 18 #include "bitarray.h" 19 #include "main.h" 20 21 #include <linux/bitmap.h> 22 23 #include "log.h" 24 25 /* shift the packet array by n places. */ 26 static void batadv_bitmap_shift_left(unsigned long *seq_bits, s32 n) 27 { 28 if (n <= 0 || n >= BATADV_TQ_LOCAL_WINDOW_SIZE) 29 return; 30 31 bitmap_shift_left(seq_bits, seq_bits, n, BATADV_TQ_LOCAL_WINDOW_SIZE); 32 } 33 34 /** 35 * batadv_bit_get_packet - receive and process one packet within the sequence 36 * number window 37 * @priv: the bat priv with all the soft interface information 38 * @seq_bits: pointer to the sequence number receive packet 39 * @seq_num_diff: difference between the current/received sequence number and 40 * the last sequence number 41 * @set_mark: whether this packet should be marked in seq_bits 42 * 43 * Return: true if the window was moved (either new or very old), 44 * false if the window was not moved/shifted. 45 */ 46 bool batadv_bit_get_packet(void *priv, unsigned long *seq_bits, 47 s32 seq_num_diff, int set_mark) 48 { 49 struct batadv_priv *bat_priv = priv; 50 51 /* sequence number is slightly older. We already got a sequence number 52 * higher than this one, so we just mark it. 53 */ 54 if (seq_num_diff <= 0 && seq_num_diff > -BATADV_TQ_LOCAL_WINDOW_SIZE) { 55 if (set_mark) 56 batadv_set_bit(seq_bits, -seq_num_diff); 57 return false; 58 } 59 60 /* sequence number is slightly newer, so we shift the window and 61 * set the mark if required 62 */ 63 if (seq_num_diff > 0 && seq_num_diff < BATADV_TQ_LOCAL_WINDOW_SIZE) { 64 batadv_bitmap_shift_left(seq_bits, seq_num_diff); 65 66 if (set_mark) 67 batadv_set_bit(seq_bits, 0); 68 return true; 69 } 70 71 /* sequence number is much newer, probably missed a lot of packets */ 72 if (seq_num_diff >= BATADV_TQ_LOCAL_WINDOW_SIZE && 73 seq_num_diff < BATADV_EXPECTED_SEQNO_RANGE) { 74 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 75 "We missed a lot of packets (%i) !\n", 76 seq_num_diff - 1); 77 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 78 if (set_mark) 79 batadv_set_bit(seq_bits, 0); 80 return true; 81 } 82 83 /* received a much older packet. The other host either restarted 84 * or the old packet got delayed somewhere in the network. The 85 * packet should be dropped without calling this function if the 86 * seqno window is protected. 87 * 88 * seq_num_diff <= -BATADV_TQ_LOCAL_WINDOW_SIZE 89 * or 90 * seq_num_diff >= BATADV_EXPECTED_SEQNO_RANGE 91 */ 92 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 93 "Other host probably restarted!\n"); 94 95 bitmap_zero(seq_bits, BATADV_TQ_LOCAL_WINDOW_SIZE); 96 if (set_mark) 97 batadv_set_bit(seq_bits, 0); 98 99 return true; 100 } 101